The present invention relates to a primable catheter system for use in any targeted drug delivery procedure including convection-enhanced delivery (CED) and chronic intracranial administrations. CED is the continuous injection under positive pressure of a fluid containing a therapeutic agent. This technique is especially useful for administering therapeutic agents to tissues that inaccessible via traditional oral medications or venous infusion techniques. For example, for central nervous system (CNS) applications, drug delivery by systemic or by intrathecal methods is not very effective because of the blood-brain barrier and limitations with regard to the drug diffusion into the tissue. At best, traditional methods of treatment result in incomplete, non-targeted and heterogeneous dispersion throughout the CNS.
CED may be used to overcome some of the restrictions associated with traditional and other delivery systems. CED utilizes a pressure gradient to infuse substances directly into the interstitial space of a target tissue, for example a solid tumor tissue, via a catheter. This process is known as interstitial infusion and relies on bulk, convective flow and can be used to distribute both small and large molecular weight substances over clinically relevant volumes within solid tissue. Additional benefits include the ability to deliver the therapeutic at relatively constant concentrations throughout the volume of distribution.
Unfortunately, the present state of the technology for CED is unable to control fluid leakage into the brain interstitial space, and in particular control serious side effects caused by fluid leakage into the cerebrospinal fluid (CSF) and other vital regions. Fluid leakage commonly follows tissue damage incurred during insertion of the catheter into the target tissue. Due to the small gauge of the catheter, a rigid catheter guide is used with the catheter to guide the catheter into position. Upon insertion of the catheter, the catheter guide cuts through the target tissue resulting in trauma and tissue damage. As the fluid is injected through the catheter, the fluid leaks into the damaged tissue resulting in undesirable and serious side effects.
Another CED concern is air bubble formation and entrapment in the catheter line that causes therapeutic problems due to incomplete drug delivery to the intended target. As air within the catheter is injected into the target tissue, an air pocket is formed into which the therapeutic agent pools and distributes unevenly. Additionally, use of a catheter guide creates space between the target tissue and the outer surface of the catheter which results in retrograde flow of the therapeutic. Retrograde flow may result in underexposure of the intended target tissue with the therapeutic agent.
Thus, while methods currently exist for CED applications, challenges still exist. Accordingly, there is a need in the art for a primable catheter system that provides bulk delivery of therapeutics without the drawbacks of currently available methods. Such a primable catheter system is disclosed herein.